Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A method for determining in-phase (I) and Quadrature (Q) imbalance (IQ imbalance) parameters based on a known signal in a dual-carrier receiver using at least one controllable frequency offset, the method comprising: receiving the known signal modulated onto a first radio frequency (RF) carrier frequency and a second RF carrier frequency different than the first RF carrier frequency; downconverting the known signal to a baseband signal for each of the first and second carrier frequencies by conversion from the respective RF carrier frequencies to an intermediate frequency (IF) using an RF local oscillator (LO) and by further conversion from IF to baseband using carrier specific IF LOs, wherein a controllable frequency offset is used as a part of the conversion from at least one of RF to IF and IF to baseband through the LOs; removing any controllable frequency offset from the baseband signal for each of the first and second carrier frequencies to produce representations of the received signals of the first and second carrier frequencies; and deriving IQ imbalance parameters based upon each representation of the received signals of the first and second carrier frequencies.
A method for estimating IQ imbalance in a dual-carrier receiver uses a known signal. This method involves receiving the known signal, which is modulated onto two different radio frequencies (RF). During downconversion, the signal goes from RF to an intermediate frequency (IF) and then to baseband, utilizing a common RF local oscillator (LO) and carrier-specific IF LOs. A controllable frequency offset is introduced during either the RF to IF or IF to baseband conversion. The method then removes this controllable frequency offset from the baseband signal for both carriers. Finally, IQ imbalance parameters are derived based on the processed signal representations of both carriers.
2. The method of claim 1 , wherein the controllable frequency offset is introduced into the conversion from RF to IF using a RF LO.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver described previously, the controllable frequency offset, which is introduced during downconversion from RF to baseband, is specifically introduced during the conversion from RF to IF. This is achieved by incorporating the controllable frequency offset into the RF local oscillator (LO) used in the RF to IF mixing stage. The method involves receiving the known signal, modulated onto two different RFs, downconverting with the offset, removing the offset, and deriving IQ imbalance parameters.
3. The method of claim 1 , wherein the controllable frequency offset is introduced into the conversion from IF to baseband using an IF LO.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver, the controllable frequency offset, which is introduced during downconversion from RF to baseband, is specifically introduced during the conversion from IF to baseband. This is achieved by incorporating the controllable frequency offset into the IF local oscillator (LO) used in the IF to baseband mixing stage. The method involves receiving the known signal, modulated onto two different RFs, downconverting with the offset, removing the offset, and deriving IQ imbalance parameters.
4. The method of claim 1 , wherein the controllable frequency offset is introduced into the conversion from RF to IF using a RF LO, and IF to baseband using an IF LO.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver, the controllable frequency offset, which is introduced during downconversion from RF to baseband, is introduced in two stages: during the conversion from RF to IF and also during the conversion from IF to baseband. This is achieved by incorporating the controllable frequency offset into both the RF local oscillator (LO) and the IF LOs. The method involves receiving the known signal, modulated onto two different RFs, downconverting with the offset, removing the offset, and deriving IQ imbalance parameters.
5. The method of claim 4 , wherein the controllable frequency offset is the same for the RF LO and IF LO functions.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver where a controllable frequency offset is introduced during both RF to IF and IF to baseband conversions, the controllable frequency offset applied to the RF local oscillator (LO) is the same value as the controllable frequency offset applied to the IF LO. The method involves receiving the known signal, modulated onto two different RFs, downconverting with the same offset in both stages, removing the offset, and deriving IQ imbalance parameters.
6. The method of claim 1 , wherein the controllable frequency offset is a non-zero value when the known signal is a synchronization (SCH) signal.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver, when the known signal is a synchronization signal (SCH), the controllable frequency offset, introduced during downconversion, is a non-zero value. The method involves receiving the SCH signal, modulated onto two different RFs, downconverting with a non-zero offset, removing the offset, and deriving IQ imbalance parameters.
7. The method of claim 6 , wherein the controllable frequency offset is zero when the known signal is a physical downlink shared channel (PDSCH) signal.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver, when the known signal is a physical downlink shared channel (PDSCH) signal, the controllable frequency offset, introduced during downconversion, is set to zero. This contrasts with the synchronization signal (SCH) where a non-zero offset is used. The method involves receiving the PDSCH signal, modulated onto two different RFs, downconverting with a zero offset, removing the offset (which is zero), and deriving IQ imbalance parameters.
8. The method of claim 1 , wherein the controllable frequency offset is removed in the frequency domain.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver, the process of removing the controllable frequency offset from the baseband signal for each carrier is performed in the frequency domain. This means that a frequency-domain representation of the signal is used to identify and remove the introduced offset. The method involves receiving the known signal, modulated onto two different RFs, downconverting with the offset, removing the offset in the frequency domain, and deriving IQ imbalance parameters.
9. The method of claim 1 , wherein the known signal is a pilot signal received by the dual-carrier receiver over-the-air.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver, the known signal is a pilot signal that is received by the dual-carrier receiver over the air. This pilot signal is transmitted wirelessly to the receiver. The method involves receiving the over-the-air pilot signal, modulated onto two different RFs, downconverting with the offset, removing the offset, and deriving IQ imbalance parameters.
10. The method of claim 1 , wherein the known signal is a test signal generated inside of an apparatus that houses the dual-carrier receiver.
In the method for estimating IQ imbalance parameters using a known signal in a dual-carrier receiver, the known signal is a test signal that is generated internally within the same apparatus that houses the dual-carrier receiver. This signal is not received over the air. The method involves receiving the internally generated test signal, modulated onto two different RFs, downconverting with the offset, removing the offset, and deriving IQ imbalance parameters.
11. An apparatus to calculate in-phase (I) and quadrature (Q) imbalance (IQ imbalance) parameters from a received known signal, the apparatus comprising: a dual-carrier receiver operative to, receive a known signal, modulated onto a first and a second radio frequency (RF) using at least one controllable frequency offset, and generate a representation of the received known signal by removing the at least one controllable frequency offset; and an IQ imbalance parameter estimator circuit operative to, receive the representation of the received known signal, and generate at least one IQ imbalance parameter based upon the representation of the received known signal generated by the dual-carrier receiver.
An apparatus estimates IQ imbalance using a known signal. It contains a dual-carrier receiver that receives a known signal modulated onto two different radio frequencies (RF) with a controllable frequency offset. The receiver removes the frequency offset, generating a representation of the received signal. An IQ imbalance parameter estimator then receives this representation and calculates IQ imbalance parameters based on it. The apparatus utilizes the controllable frequency offset during signal reception and processing to improve IQ imbalance estimation.
12. The apparatus of claim 11 , wherein the dual-carrier receiver comprises: a RF mixer operative to receive the known signal and mix the known signal with a RF local oscillator (LO) to produce a first result; a first intermediate frequency (IF) mixing stage including, a first IF mixer operative to receive the first result from the RF mixer and mix the first result with an IF LO to generate an output, a first complex conjugate unit operative to receive the first result from the RF mixer and generate a complex conjugate of the first result, a second IF mixer operative to receive the complex conjugate of the first result from the first complex conjugate unit and mix the complex conjugate of the first result with an IF LO to generate an output, and an first adder operative to add the outputs of the first and second IF mixers; a first low pass filter operative to receive added outputs of the first and second IF mixers and generate a baseband representation of the known signal; a second IF mixing stage including, a third IF mixer operative to receive the first result from the RF mixer and mix the first result with an IF LO to generate an output, a second complex conjugate unit operative to receive the first result from the RF mixer and generate a complex conjugate of the first result, a fourth IF mixer operative to receive the complex conjugate of the first result from the second complex conjugate unit and mix the complex conjugate of the first result with an IF LO to generate an output, and an second adder operative to add the outputs of the third and fourth IF mixers; and a second low pass filter operative to receive added outputs of the third and fourth mixers and generate a baseband representation of the known signal; wherein at least one of the RF or IF LOs includes a frequency offset.
The invention relates to a dual-carrier receiver apparatus designed to process a known signal in wireless communication systems. The apparatus addresses the challenge of accurately demodulating signals in environments where frequency offsets or interference may degrade performance. The receiver includes an RF mixer that receives the known signal and mixes it with an RF local oscillator (LO) to produce an intermediate result. This result is then processed in two parallel intermediate frequency (IF) mixing stages. Each stage includes a pair of IF mixers, where one mixer processes the original intermediate result while the other processes its complex conjugate. The outputs of these mixers are combined using adders, and the combined signals are filtered by low-pass filters to generate baseband representations of the known signal. The dual-stage design enhances signal integrity by mitigating phase and frequency distortions. At least one of the RF or IF LOs incorporates a frequency offset to compensate for carrier frequency mismatches or Doppler shifts, improving synchronization and demodulation accuracy. The apparatus is particularly useful in applications requiring robust signal recovery in dynamic or noisy environments.
13. The apparatus of claim 11 , further comprising: orthogonal frequency-division multiplexing (OFDM) circuitry operative to remove a frequency offset of an RF LO or IF LO.
An apparatus for estimating IQ imbalance parameters, including a dual-carrier receiver that receives signals modulated with a controllable frequency offset and an IQ imbalance estimator, also includes orthogonal frequency-division multiplexing (OFDM) circuitry. This OFDM circuitry is used to remove the frequency offset introduced by either the RF local oscillator (LO) or the IF LOs. Thus, the system leverages OFDM processing to compensate for frequency offsets during IQ imbalance estimation.
14. The apparatus of claim 11 , further comprising: memory to store the controllable frequency offsets of the RF LOs or IF LOs.
An apparatus for estimating IQ imbalance parameters, including a dual-carrier receiver that receives signals modulated with a controllable frequency offset and an IQ imbalance estimator, also includes memory. This memory is used to store the values of the controllable frequency offsets used by the RF local oscillators (LOs) or the IF LOs. Storing these offset values enables accurate removal and compensation during IQ imbalance estimation.
15. A system, comprising: an Evolved Node B (eNodeB) that transmits pilot signals; and a receiver device communicatively coupled with the eNodeB that calculates in-phase (I) and quadrature (Q) imbalance (IQ imbalance) parameters based upon the pilot signals, wherein the receiver device comprises, a dual-carrier receiver that, receives the pilot signals transmitted by the eNodeB, wherein each of the pilot signals is modulated onto a first and a second radio frequency (RF) using at least one controllable frequency offset, and generates representations of the received pilot signals by, for each pilot signal, removing the at least one controllable frequency offset; and an IQ imbalance parameter estimator circuit coupled to the dual-carrier receiver that, receives the representations of the received pilot signals from the dual-carrier receiver, and generates, for each of the representations of the received pilot signals and based upon each representation, at least one IQ imbalance parameter.
A system for IQ imbalance estimation consists of an Evolved Node B (eNodeB) and a receiver device. The eNodeB transmits pilot signals. The receiver device receives these pilot signals and calculates IQ imbalance parameters. The receiver device includes a dual-carrier receiver that receives pilot signals modulated onto two different radio frequencies (RF) using controllable frequency offsets. It removes these offsets to generate representations of the received pilot signals. An IQ imbalance parameter estimator then uses these representations to generate IQ imbalance parameters.
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September 23, 2014
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